An image processing apparatus including a controller for controlling a print execution unit. The print execution unit repeatedly performs ejection processing of ejection droplet of color material onto a printing medium. The controller is configured to perform: specifying an estimate value for a target pixel image by using at least one pixel value corresponding to at least one of a plurality of pixels included in target partial data representing the target partial image, the target partial image being selected among a plurality of partial images included in an N-th band image and representing a part of an object; specifying an object type of the object; and determining an ejection execution direction with respect to an N-th ejection processing to be one of a first direction and a second direction according to the estimate value and the object type.
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1. An image processing apparatus for controlling a print execution unit, wherein the print execution unit including: a print head having a plurality of nozzle groups corresponding to a plurality of color material and arranged in a main scanning direction, each of the plurality of nozzle groups comprising a plurality of nozzles arranged in a sub-scanning direction, each of the plurality of nozzles being configured to eject a droplet of color material onto a printing medium, the image processing apparatus comprising a controller configured to perform: acquiring image data; determining an ejection execution direction of the print head for each of a plurality of pieces of band image data, the image data including the plurality of pieces of band image data representing a plurality of band images arranged in the sub-scanning direction, the ejection execution direction being one of a first direction and a second direction, the first direction being parallel to the main scanning direction, the second direction being parallel to the main scanning direction and opposite to the first direction; and controlling the print execution unit to form an image according to the image data, the print execution unit repeatedly performing an ejection processing of ejecting the droplet of color material onto the printing medium and conveying the printing medium in the sub-scanning direction, an N-th ejection processing forming an N-th band image of the plurality of band images according to N-th band image data of the plurality of pieces of band image data, the N-th ejection processing being performed by moving the print head in the ejection execution direction successively after an (N−1)-th ejection processing is performed, wherein the controller is further configured to perform: specifying an estimate value for a target partial image by using at least one pixel value, the target partial image being selected among a plurality of partial images included in the N-th band image, target partial data representing the target partial image and including a plurality of pixels, each of the plurality of pixels having a pixel value, the at least one pixel value corresponding to at least one of the plurality of pixels included in the target partial data, the target partial image representing a part of an object; and specifying an object type of the object among a plurality of object types including a first object type and a second object type; wherein the estimate value represents a color gap between a first printed image and a second printed image, wherein the first printed image is an image according to the target partial data and printed by performing the ejection processing with moving the print head in the first direction whereas the second printed image is an image according to the target partial data and is printed by performing the ejection processing with moving the print head in the second direction; and wherein the controller is further configured to perform: determining the ejection execution direction with respect to the N-th ejection processing to be one of the first direction and the second direction according to the estimate value and the object type, where N is an integer equal to or greater than 2.
An image processing system controls a print head to print images on a medium. The print head has multiple nozzle groups for different color materials, arranged side-by-side. Each nozzle group has nozzles arranged in a line. The system acquires image data and determines whether the print head should move left-to-right (first direction) or right-to-left (second direction) for each band of the image. This decision is made by estimating a color gap for small sections ("partial images") within each band. The system identifies the object type (e.g., text, graphic) within these partial images. Based on the estimated color gap and the object type, the system chooses the printing direction to minimize color artifacts and improve image quality.
2. The image processing apparatus according to claim 1 , wherein, when the first object type is specified, the controller is further configured to perform: determining whether the estimate value satisfies a first condition, the first condition indicating that a color gap between a third printed image and a fourth printed image is recognizable, the third printed image including a part of an object of the first object type and being printed by performing the ejection processing with moving the print head in the first direction, the fourth printed image including the part of the object of the first object type and being printed by performing the ejection processing with moving the print head in the second direction; determining the ejection execution direction with respect to the N-th ejection processing to be the first direction in response to determining that the estimate value satisfies the first condition; and determining the ejection execution direction with respect to the N-th ejection processing to be opposite to the ejection execution direction with respect to the (N−1)-th ejection processing in response to determining that the estimate value does not satisfy the first condition, wherein, when the second object type is specified, the controller is further configured to perform: determining whether the estimate value satisfies a second condition, the second condition indicating that a color gap between a fifth printed image and a sixth printed image is recognizable, the fifth printed image including a part of an object of the second object type and being printed by performing the ejection processing with moving the print head in the first direction, the sixth printed image including the part of the object of the second object type and being printed by performing the ejection processing with moving the print head in the second direction; determining the ejection execution direction with respect to the N-th ejection processing to be the first direction in response to determining that the estimate value satisfies the second condition; and determining the ejection execution direction with respect to the N-th ejection processing to be opposite to the ejection execution direction with respect to the (N−1)-th ejection processing in response to determining that the estimate value does not satisfy the second condition.
In the image processing system of claim 1, when the system identifies a "character" object type, it checks if the estimated color gap is above a threshold indicating noticeable color differences between left-to-right and right-to-left printing. If the gap is above the threshold, the system prints the current band left-to-right. If the gap is below the threshold, it prints the current band in the opposite direction of the previous band. When the object type is "non-character," a different threshold for color gap is used. The system prints left-to-right if the color gap exceeds this second threshold, and reverses direction otherwise. This optimizes print direction based on object type and perceived color errors.
3. The image processing apparatus according to claim 2 , wherein the estimate value associated with the target partial image represents an estimate value of a gap between a seventh printed image and a eighth printed image, wherein the seventh printed image is the target partial image printed by performing the ejection processing with moving the print head in the first direction whereas the eighth printed image is the target partial image printed by performing the ejection processing with moving the print head in the second direction.
The image processing system of claim 2 calculates the "estimate value" used to decide printing direction by comparing the printed output of a small image area ("target partial image") when printed left-to-right versus the printed output of the same area when printed right-to-left. The "estimate value" therefore represents how much the appearance of that specific partial image changes depending on print direction. This gap is then used to decide printing direction, as detailed in claim 2, depending on the object type.
4. The image processing apparatus according to claim 3 , wherein the controller is further configured to perform: determining the estimate value by using information relevant to a color gap perceived by an observer who visually observes a ninth printed image and a tenth printed image, wherein the ninth printed image is printed according to a pixel value by performing the ejection processing with moving the print head in the first direction whereas the tenth printed image is printed according to the same pixel value as the ninth printed image by performing the ejection processing with moving the print head in the second direction.
The image processing system of claim 3 calculates the "estimate value" (color gap) based on how a human observer would perceive the difference between two printed versions of the same pixel data, one printed left-to-right, and the other right-to-left. The system uses information relevant to the color gap perceived by the observer, when determining the color gap to minimize visible artifacts.
5. The image processing apparatus according to claim 3 , wherein the first condition includes that a color gap between the third printed image and the fourth printed image is equal to or more than a first reference value; and wherein the second condition includes that a color gap between the fifth printed image and the sixth printed image is equal to or more than a second reference value.
In the image processing system of claim 3, the system decides print direction by comparing the estimated color gap against thresholds. For "character" objects (third and fourth printed images of claim 2), the system only prints left-to-right if the color gap is greater than or equal to a first reference value. For "non-character" objects (fifth and sixth printed images of claim 2), it only prints left-to-right if the color gap is greater than or equal to a second, potentially different, reference value.
6. The image processing apparatus according to claim 1 , wherein the controller is further configured to perform: determining a reference position on the N-th band image and determining a position of each of the plurality of partial images according to the reference position.
In the image processing system of claim 1, the system determines a reference position on each band image and calculates the position of each small image area ("partial image") relative to that reference point. This allows the system to consistently analyze the same regions of each band and correctly evaluate the color gap for each partial image, regardless of minor alignment variations.
7. The image processing apparatus according to claim 2 , wherein the first object type indicates a character, and the second object type indicates an object type different from the character; wherein the controller is further configured to perform: specifying the estimate value by common values irrespective of an object type; and wherein, when the estimate value is represented by at least a part of the common values, the estimate value does not satisfy the first condition but satisfies the second condition.
In the image processing system of claim 2, the first object type represents "characters" and the second object type represents objects other than characters. The system calculates initial, object-independent ("common") color gap values. Critically, the system is designed such that if the common color gap values were directly used, "character" objects would *not* trigger a direction change while "non-character" objects *would*.
8. The image processing apparatus according to claim 7 , wherein the first condition includes that the estimate value is equal to or more than a first threshold; and wherein the second condition includes that the estimate value is equal to or more than a second threshold.
In the image processing system of claim 7, the system compares the estimated color gap to a first threshold for character objects, printing left-to-right only if the gap is equal to or greater than this threshold. For non-character objects, the system uses a second threshold, which may be different, to determine the printing direction.
9. The image processing apparatus according to claim 7 , wherein the controller is further configured to perform: specifying the estimate value by multiplying the common values by a first weight when the first object type is specified; and specifying the estimate value by multiplying the common values by a second weight when the second object type is specified, the second weight being greater than the first weight.
In the image processing system of claim 7, the system calculates a base color gap value that is the same for all object types ("common values"). However, when the system identifies a "character," it multiplies the base value by a first weight. When the system identifies a "non-character" object, it multiplies the base value by a second weight, which is greater than the first weight. This adjusts the color gap differently for different object types.
10. The image processing apparatus according to claim 1 , wherein the controller is further configured to perform: classifying the plurality of partial images into object partial images each including at least a part of an object and blank partial images each including no objects; and specifying the estimate value for each of the plurality of partial images other than the blank partial images.
In the image processing system of claim 1, the system classifies each of the small sections of the image band ("partial images") as either "object partial images" containing at least part of an object, or as "blank partial images" containing no objects. The system only calculates the estimated color gap and makes printing direction decisions for the "object partial images," skipping calculations for blank regions to improve efficiency.
11. The image processing apparatus according to claim 1 , wherein in the print head, the plurality of nozzle groups includes a first nozzle group having a plurality of first nozzles and a second nozzle group having a plurality of second nozzles; wherein in the ejection processing in the first direction, when the print head is moved in the first direction, the plurality of first nozzles ejects a droplet of first color material onto the print medium and the plurality of second nozzles successively ejects a droplet of second color material onto the print medium; and wherein in the ejection processing in the second direction, when the print head is moved in the second direction, the plurality of second nozzles ejects a droplet of second color material onto the print medium and the plurality of first nozzles successively ejects a droplet of first color material onto the print medium.
In the image processing system of claim 1, the print head has at least two nozzle groups: a first group with nozzles that eject a first color, and a second group that ejects a second color. When printing left-to-right, the first color is applied before the second color. When printing right-to-left, the second color is applied before the first color. This nozzle arrangement is related to the perceived color gaps that are minimized by the invention.
12. The image processing apparatus according to claim 1 , wherein in the print head, the plurality of nozzle groups includes L nozzle groups and each of the L nozzle groups ejects a droplet of color material different from each other, where L is an integer equal to or greater than 2.
In the image processing system of claim 1, the print head includes L nozzle groups (where L is 2 or more). Each of these nozzle groups ejects a different color material onto the printing medium. The system is capable of switching print direction (left-to-right or right-to-left) on a per-band basis to improve color accuracy and image quality, regardless of the number of different color materials.
13. A non-transitory computer readable storage medium storing a set of program instructions installed on and executed by a controller, the program instructions, when executed by the controller, causing the controller to control an print execution unit to perform forming an image, the print execution unit including a print head having a plurality of nozzle groups corresponding to a plurality of color material and arranged in a main scanning direction, each of the plurality of nozzle groups comprising a plurality of nozzles arranged in a sub-scanning direction, each of the plurality of nozzles being configured to eject a droplet of color material onto a printing medium, the controller being configured to control an image processing apparatus to perform: acquiring image data; determining an ejection execution direction of the print head for each of a plurality of pieces of band image data, the image data including the plurality of pieces of band image data representing a plurality of band images arranged in the sub-scanning direction, the ejection execution direction being one of a first direction and a second direction, the first direction being parallel to the main scanning direction, the second direction being parallel to the main scanning direction and opposite to the first direction; and controlling the print execution unit to form an image according to the image data, the image data, the print execution unit repeatedly performing ejection processing of ejecting the droplet of color material onto the printing medium and conveying the printing medium in the sub-scanning direction, an N-th ejection processing forming an N-th band image of the plurality of band images according to N-th band image data of the plurality of pieces of band image data, the N-th ejection processing being performed by moving the print head in the ejection execution direction successively after an (N−1)-th ejection processing is performed, wherein the program instructions further comprise controlling the image processing apparatus to perform: specifying an estimate value for a target partial image by using at least one pixel value, the target partial image being selected among a plurality of partial images included in the N-th band image, target partial data representing the target partial image and including a plurality of pixels, each of the plurality of pixels having a pixel value, the at least one pixel value corresponding to at least one of the plurality of pixels included in the target partial data, the target partial image representing a part of an object; and specifying an object type of the object among a plurality of object types including a first object type and a second object type; wherein the estimate value represents a color gap between a first printed image and a second printed image, wherein the first printed image is an image according to the target partial data and printed by performing the ejection processing with moving the print head in the first direction whereas the second printed image is an image according to the target partial data and is printed by performing the ejection processing with moving the print head in the second direction; and wherein the controller is further configured to perform: determining the ejection execution direction with respect to the N-th ejection processing to be one of the first direction and the second direction according to the estimate value and the object type, where N is an integer equal to or greater than 2.
A non-transitory computer-readable storage medium stores instructions that, when executed, cause a controller to control a printing system similar to claim 1. The instructions cause the system to acquire image data, determine a printing direction (left-to-right or right-to-left) for each band of the image, based on estimated color gaps and object types within each band. The "estimate value" represents a color gap between a first printed image (left-to-right) and a second printed image (right-to-left). The direction is chosen to reduce color artifacts.
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March 31, 2016
March 28, 2017
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